Heat transfer Definition and 947 Threads

You are given a solid, homogenous block of material, 48x24x12 inches suspended in air at 70 degrees. The block is initially at 70 degrees as well. Then, a laser is used to heat one corner of the block to a constant 200 degrees. Model the heat transfer through the block and report the average...

Homework Statement The geometry is attached (an L shaped 2d plate) taking del_x = del_y = 0.5mm, using finite-volume techniques, construct a MATLAB program to calculate steady state temps as well as heat transfer for the full 2d geometry. Tambient = (15+273)K Homework Equations use...

If I stand at the corner of a largely room with a room-temperature and burn something with flames for few seconds, it'll hardly change the temperature of the other corner far away. Yet, If I whistled event softly it could be clearly heard at any point in the room -instantly-. Each phenomena...

Homework Statement a thick walled tube of stainless steel, ks=19W/m.K, with a 2cm internal diameter and a 4cm outer diameter is covered with a 3cm thick layer of insulation. If the inside and outside wall temperatures are 600C and 100C respectively and the thermal conductivity of the...

If I had a piece of steel 0.25" thick 1 meter wide and 1 meter long and it was at 100 deg C and it was immersed in a bath of zinc at 460 deg C how long would it take to heat the piece of steel to 460 deg C? Would this be down the lines of Fourier's Law of conduction? q=...

Hi all. Why Reynolds Analogy and other empirical relations always overesimate heat transfer? I have done an experiment on turbulent pipe flow (smooth pipe) and I used Reynold Analogy (both the simple (Pr=1) and the modified one) and the Dittus-Boetler correlation equation to do the...

I got into a discussion about heat sink materials and was beaten up for suggesting that Aluminum is better than Copper because it will transfer the heat away from itself much faster than copper. Copper has about half the specific heat and about twice the thermal conductivity over Aluminum. Am...

Hi, I have to determined the rate of heat transfer in a delivery dock when the big garage doors are open. I have tried a natural convection approach, but I lack the mass air flow from the inside of the garage (22°C) to the outside (-10°C). Or is there another way to calculate this? Thanks...

Heat transfer and Fluid Mechanics, COMSOL Help Hello, I am trying to couple heat transfer and fluid mechanic together, model is a simple concrete slab (3'x6')with a water pipe beneath it and along 3' direction. For heat transfer, the heat flux will apply on the surface of concrete slab...

Heat does not naturally flow from a cool body to a hot body. A refrigerator, however, does remove heat from the icebox and expels it as warm air to the outside world. What is required to make this process function?

Homework Statement a rectangular plate (15 x 30) with the following boundary conditions: u_y(x,0) = 0 u_y(x,30) = 0 u_x(0,y) = 0 u_x(15,y) = y(20-y) the derivative B.Cs describe the heat flux through the boundaries. solve the the steady-state temp u(x,t) Homework Equations...

Homework Statement A 300 cm3 glass is filled with 120 g of ice at 0°C and 210 g of water at 25°C. (a) Characterize the content of the glass after equilibrium has been reached. Neglect heat transfer to and from the environment. Find: mass of water? mass of ice...

Not sure where to put this post, care more about what's happening on atomic scaI le so i put it here. I am currently taking Heat transfer for engineers and we were discussing the mechanicals for heat transfer, conduction, convection, raditation. In class my professor said that conduction is...

I am currently enrolled in a course on Spacecraft Thermal Control, and, in addition to the Satellite Thermal Control Handbook, we are to purchase a book on heat transfer to use as a reference for the course. Does anyone have any recommendations? Listed below are some of the ones the professor...

A piece of metal with a mass of 1.50 kilograms, specific heat of 200 J/kg · C°, and initial temperature of 100° C is dropped into an insulated jar that contains liquid with a mass of 3.00 kilograms, specific heat of l,000 J/kg · C°, and initial temperature of 0° C. The piece of metal is removed...

How does heat tranfer in motional bodies? Homework Equations The Attempt at a Solution

If I have a fluid, initial temperature and flow rate known (and constant), that is flowing through a heating element (heat given in Watts), what equation do I use to determine how long it takes the fluid to reach a certain temperature? This is a transient problem, for a closed loop system.

Hi guys, Hoping to see if I can get a bit of help with a heat transfer equation. Apologies if this is not in the correct forum as this is my first post. I need to find out how long it will take a bag of 1000L of water (in a 1m3 cubic bag) to heat up to a specific temperature. The bag is...

First off I would like to say that this is not a homework question. I am trying to calculate the temperature of a very thin piece of steel. Assumptions The underside of the metal is perfectly insulated To = 20C (initial temperature of material) Q"=3000W/m^2 (heat flux) K = 51.9W/m*K...

My first posting, so apologies if this is in any way inappropriate to the forum/section. I am asking here for some scientific input to this question about a cooling system as, for example found in a classical motor vehicle; what is the likely relationship between coolant flow and heat...

As I remember learning in school, heat cannot flow from cold to hot. But isn't that true only for conduction and convection? Radiation heat is purely Infrared waves, and there should not be any issue with that. Please correct if I am wrong.

I need a hand understanding the behaviour of a system which follows: Hot combustion gases emerge from an aperture at a fixed temperature and pressure and pass through a length of tube. How does the diameter of the aperture and tube, plugged into bernoulli's principle, turbulence of the gas...

Hi, I want to know the peak temperature attained and temperature distribution with time in a frictional welding process ( ultrasonic consolidation between an Al substrate and Al strip). The problem with normal thermocouples is that by the time it shows the temperature , the temperature has...

this question was posed by someone on a computer forum and is probably easy for some of you, so here goes : imagine water in an open container which is perfectly insulated on the sides and bottom. the water is stationary and heat is being added from the top (assume that the surroundings above...

We are compounds of peroxide cure insulation materials and often get asked by customers on recommendations for processing conditions and more often then not our answers is the very not commital "It depends". Lots of factors are needed to be taken into consideration when processing our...

I noticed that my tea heats up faster than the cup it's in when I microwave it... how come? aren't solids more conductive? Also... I was wondering how the notion of vibrating atoms/electrons (heat) squares with quantum mechanics, probability waves and such?

From what I gathered in Heat transfer, an object in space, ie space shuttle, can only lose cabin heat through the means of radiation (no conduction or convection off the surface...) So how would one go about determining what the emissivity is in space. Obviously there will be objects that are...

When room temperature is at 19 degree centigrade, I found that water temperature is at about 20 degree centigrade a small plastic cup at volume of 3ml, filled with 1ml of water, put in a secluded shaker at the temperature of 42 degree centigrade, , what should the water temperature...

I'm working on a project that involves putting electronics equipment into a solid metal (aluminum) case. The cases are sealed watertight and I need to be able to transfer the heat originated at the electrical components to the ambient air. I can perform the analysis to get a pretty good idea...

I'm in need of an equation that relates the loss of heat (in power) of a cable to ambient air to various parameters such as diameter, temperatures of air and cable, and all other variable that may play a role. My research online has produced some results, but I haven't quite found what I'm...

Homework Statement We have a wall of 30cm thickness, an inner surface temp of 500Kelvins and outer surfce temperature of 60Kelvins. Homework Equations thermal conductivity = k(a) = 60 + 0.0006a^2, where a = temperature. fouriers law = q = -kA(da/dx) The Attempt at a Solution...

Hi, I have nothing to do this summer so I figured I would like to model the heat transfer for different shapes and fluids and compare with experimental values.. :) Anyway I searched on google and found nothing. What are the main problems? For example is it acceptable to assume that the...

THe question is : Given the reaction CH3OH goes to CO + 2H2 Change in heat=90.7 a)endothermic or exothermic? b)Calculate amount of heat transferred when 45 g. of CH3OH id decomposed by this reaction at constant pressure. c)For a given sample of CH3OH the enthalpy...

The problem is about a cylinder with 3 mm thickness in the walls, roof, and ceiling. The walls, roof, and ceiling also have a k value of .0042 w/mk. Inside the cylinder is 64 degrees Celsius and outside its 22 degrees Celsius. The air outside the cylinder has a heat transfer coefficient of .3...

Im doing a project to put a heater in a car to pre heat it. I need to determine how many watts would be needed to defrost a window in a certain amount of time. I know the temp of the outside air and temperature to melt the ice is at least 0 C. I thought i could use it as a semi- infinite...

Homework Statement Find the amount of thermal energy that flows per day through a solid oak wall 10.0 cm thick, 3.00 m long, and 2.44 m high, if the temp of the inside wall is 21.1 C while the temp of the outside wall is -6.67 C. Homework Equations Q= k(A)(T2-T1)t/d coefficient of...

Hi all I've been calculating heat convection off a horizontal heated plate to still cool air around it. Since the plate has a size of 50m2 the GrPr number is turbulent i there's no equation in my book to calculate heat transfer by convection for GrPr > 10^11, so i used the equation of GrPr at...

I don't know if classical physics is the best place to put this, cause normally i would have put it in the engineering section. There is no governing equation right now to describe heat flow between 2 liquids? another question: flow between 2 liquids is governed by convection, if we place an...

Hey. I've been pondering on and off for a while now how exactly energy is transferred between two gas atoms, with different energies, via collision. Specifically how the electrons, photons, neutrons, protons, and any other particles that are used for energy transfer in convection, interact...

This is not homework, so I think this is the right forum. I am trying to write a program that simulates the heat transfer between, say two cubes of different volumes, heat capacities and thermal resistances. I know Newton's law of cooling just works dandy for say an object cooling in a fixed...

Homework Statement Rigid tank volume .5m^3 initially evacuated. Tiny hole develops, air seeps in @ 1 bar and 21 degrees C. Pressure in tank reaches 1 bar, slow leak so temp remains 21 deg C inside tank. What's amount of heat transfer? Homework Equations Q=T[S(2)-S(1)] Pv=nRT The...

In an electrical circuit, when current flows through a resistance, heat is produced. Is there some quantity (?) into which heat is transformed when it flows through a substance (all substances having some resistance to heat flow)?

ok, this is more of a question of theory than actual calculation. Me and my friends did a physics lab on heat transfer vs. surface area of contact. We used water and oil (since oil will float above the water and creating a surface of contact). We heated the water to ~50 degrees C and oil was...

im reviewing for my final in a few days an although this is a basic question i can't work out the correct answer for some reason. and i know i started the other thread below this one but i figured this was a different topic so the heading should be different lol Homework Statement A heat...

convection right?

A light breeze of 10mi/hr blows across a metal building. The buildings wall is 3.7m tall and 6.1m wide. A net energy flux of 347w/m^2 from the sun is absorbed by the wall and then dissipated to the air through convection. Assuming the air is 27c and 1 atm and blows across the wall as a flat...

A 20-20-5 cm slab of copper at a uniform temp of 200c suddenly has its surface temp lowered to 35c. Using the concepts of thermal resistance and capacitance and the lumped-capacity analysis, find the time at which the center temp becomes 90c. density =8900 kg/m^3 specific heat = .38 kJ/kg-k...

Hi can anyone temme how to calculate view factor between two spheres.

My book is fairly explicit when it comes to solving problems with rods of uniform temp, and fins that have a heat source at one end but I have a couple of HW problems that deal with rods. 1) A rod connected to 1 hot wall given: Wall temp environment temp dia. and length of rod heat...

An insulation system is to be selected for a furnace wall at 1000 deg C using first a layer of mineral wool blocks (k=.091 W/m-c) followed by fiberglass boards (k=.0425 W/m-c). The outside of the insulation is exposed to an environment with h= 15 W/m^2-c and temp of 40 deg C. Claculate the...